Death of Sun

    In between 1920 and 1930 people thought that when a star died, either it is a sun or a star, it becomes a white dwarf. There is a pair of Sirius in the universe that are Sirius A and Sirius B, which are the two stars and one of the star is a white dwarf.

 But when scientists studied it, they found that the density of white dwarf, Sirius B, is millions time greater than its own sun. Now there is a thought in our mind that why that white dwarf is not turning into a black hole? or, why it doesn't pull it's sun towards it?

 Then some scientists starts to study it, that was the time to arise of quantum mechanics, which says us that, if we take any two electron then they cannot in the same position, same size and doesn't have same properties in other words any two electrons cannot be twins.

  Just imagine that there is a sun and its density is increasing and increasing due to putting mass in it and the particles will come close to each other. Then it will happen that all the definition of atom will broke, all protons comes into one side, electron comes into other side and all the particles of atoms mix with each other but how can this will be possible if this will happen then who will stop this process because if they mix with each other then they should be destroyed because if proton and electron mix with each other then they will form neutron and all the the things will finished. But this is not happening, we can see that white dwarf which is present in the universe. Now we thought that if two things are attracting each other and no one stopping them then they should be destroyed. Now the quantum mechanics help in this situation, which says us about that any two electron cannot be twin. If this principle is true then we got an answer that if two electron starts to come into the same position then the nature by itself will separate them and that will create a pressure, which is degeneracy pressure, that pressure will want to separate the elements but the gravitational pool will says come inside, so the force will constant and the process will stop there, so when star start dying and it becomes white dwarf then that pressure protect the white dwarf from collapse.

   Now came Mr. Chandrashekhar, who is nephew of C.V. Raman, who has such a bright brain that he calculate all the things in the way from India to England. He says that if we calculate here then the situation of electron will like that the speed of electron will come near to the speed of light, it means if we increase the density then the speed of electron will pass the speed of light, but this can not be possible. So there is a limit, so he give a nice relation from that relation we found that if any star is 1.4 times of our then that is the limit of a star. So if any star is less than 1.4 time of the sun then it will become the white dwarf and if the star's mass is greater then 1.4 times of sun then no one can stop it, it's gravitational pool will be such greater that the degeneracy pressure which says that get away and get get away, this can not be stop it and eventually destroy. We know that there is nuclear  reaction in star or sun and due to this there is the formation of new element and if there all the stars will become white dwarf then there is no planets exits nowadays. So, all the stars doesn't become white dwarf after dying.